Method and apparatus for packaging objects of different types

ABSTRACT

A method comprises the steps of:positioning a plurality of objects, having different dimensions to each other, on an infeed conveyor;delivering to an intermediate conveyor a flow of objects coming from the infeed conveyor and movable along an advancement direction;feeding a packaging unit with the objects coming from the intermediate conveyor, the packaging unit producing a plurality of packages, starting from a web of packaging material, each package containing one object.The method further comprises the step of checking if, in the flow of objects which advance along the intermediate conveyor, there are empty positions in which an object is missing. If an empty position is detected, there is provided filling the empty position by accelerating the objects which follow the empty position relative to the objects which precede the empty position. The intermediate conveyor comprises a plurality of conveyor belts arranged in sequence along the advancement direction. If the number of objects arriving on the intermediate conveyor in the unit of time is greater than or equal to a predetermined value, the production speed of the packaging unit is adjusted in such a way as to keep in the intermediate conveyor a predetermined average filling level.

This invention relates to a method and an apparatus for packaging, oneafter the other, objects of different types, which consequently havedimensions generally variable between one object and the next.

The method and the apparatus according to the invention are particularlysuitable for being used in the e-commerce field, in order to packageobjects ordered using the Internet, which must be packaged before beingdelivered to the customers who have requested them.

In the e-commerce field, apparatuses are known for packaging objectsdifferent from each other, which have been ordered by various customersand must be dispatched.

The prior art apparatuses comprise a packaging machine for packagingeach object in a flexible packaging, for example an envelope. Flexiblepackaging may be made using a web of paper which, after being unwoundfrom a reel, interacts with a glue applicator which applies an adhesivesubstance to the paper. The paper is then folded around the object tomake the package and then subjected to a cutting operation forseparating a package from the next one.

Upstream of the packaging machine, there are positioned in order aninfeed conveyor on which the operators manually load the objects to bepackaged, a rejection station for rejecting non-conforming objects and aphasing conveyor for positioning the objects in such a way that betweenone object and another there is an empty space with constant dimensions.

It may happen that, in the flow of objects which enters the phasingconveyor, there are positions in which, for various reasons, an objectis missing. This may be due, for example, to the fact that an object hasbeen rejected in the rejection station, or due to the fact that anoperator has not been able to fill all the positions, or due to otherreasons.

When there is an empty position in the flow of objects which enters thephasing conveyor, that position is treated as corresponding to an objecthaving the minimum length which can be processed by the machine.

Consequently, the packaging machine produces an empty package, which hasto be then rejected.

This results in various drawbacks.

Firstly, rejecting the empty packages results in a waste of material,since the packaging material with which the empty packages are made mustbe disposed of.

Moreover, the rejected empty packages are conveyed to a temporarystorage area from which they must be periodically removed, which makesit necessary to stop the apparatus, with consequent productivity drops.

Thirdly, due to the rejecting of the empty packages it may be difficultto decide with sufficient precision the hourly productivity at which thepackaging process must be set, which will be used by the control unit ofthe apparatus to calculate the linear advancement speed of the packagingmaterial.

In prior art apparatuses, another drawback is linked to the behaviour ofthe glue if the operation of the apparatus must be stopped for anyreason. The flaps of paper to be joined by gluing must be brought intocontact with each other and subjected to an adequate pressure within apredetermined maximum time—which is usually several tens of seconds—fromthe moment the glue has been applied. If this condition is not compliedwith, the glue dries and there is no certainty that the package willremain adequately closed. Consequently, if the apparatus undergoes astoppage for longer than the period of time during which the glued jointmust be closed, the packages present in the packaging machine, whichhave not yet been subjected to pressure in order to close the gluedjoint, must be rejected. This results in wastage of packaging materialand loss of time, with a consequent reduction in productivity.

An object of the invention is to improve the methods and apparatuses forpackaging objects, particularly objects having dimensions which arevariable between one object and the next.

Another object is to reduce the waste of packaging material,particularly paper and glue.

Another object is to reduce the number of packages which must berejected, which would allow the stoppages to be minimised for removingfrom the apparatus the packages to be rejected.

Yet another object is to make the hourly productivity of the apparatusmore easily predictable.

A further object is to reduce the rejection of packages which have notbeen glued and closed in a reliable manner during the stoppages of theapparatus.

In a first aspect of the invention, there is provided a methodcomprising the steps of:

-   -   positioning a plurality of objects, having different dimensions        to each other, on an infeed conveyor;    -   delivering to an intermediate conveyor a flow of objects coming        from the infeed conveyor;    -   feeding a packaging unit with the objects coming from the        intermediate conveyor, the packaging unit producing a plurality        of packages, starting from a web of packaging material, each        package containing one of said objects;

wherein the method further comprises the step of checking if, in theflow of objects which advance along the intermediate conveyor, there areempty positions in which an object is missing and wherein, if an emptyposition is detected, there is provided filling the empty position byaccelerating the objects which follow the empty position relative to theobjects which precede the empty position.

Owing to the first aspect of the invention, the empty positions whichcould be present in the flow of objects loaded on the intermediateconveyor are filled before the objects reach the packaging unit. Thelatter may thus be fed by a continuous flow of objects, that is to say,by a flow in which there are no objects missing, which means that allthe packages produced by the packaging unit have an object inside them.

The drawback of the prior art is therefore practically eliminated, inwhich any empty positions in the flow of object entering the packagingunit resulted in empty packages, which had to be subsequently rejected.

In this way, it is possible to reduce the waste of packaging materialand minimise, or even eliminate, stoppages of the apparatus linked tothe need to remove the rejected empty packages.

Moreover, since it is no longer necessary to reject many empty packages,the number of rejected packages decreases drastically, which makes iteasier to precisely decide the hourly productivity of the apparatus.

In an embodiment, the intermediate conveyor acts as a buffer in which aplurality of objects is temporarily accumulated while waiting to enterthe packaging unit.

By using the intermediate conveyor as a buffer, the productivity of thepackaging unit may be optimised in such a way as to be less affected bythe variations which may occur in the number of objects which are loadedon the infeed conveyor to be fed on the intermediate conveyor.

In an embodiment, the intermediate conveyor comprises a plurality ofconveyor belts arranged in sequence along the advancement direction.

In an embodiment, if the number of objects arriving on the intermediateconveyor in the unit of time is greater than or equal to a predeterminedvalue, the production speed of the packaging unit is adjusted in such away as to keep in the intermediate conveyor a predetermined averagefilling level.

This allows the operation of the apparatus to be better controlled.

In particular, the packaging unit may be controlled in such a way as toproduce packages with an adaptive productivity, that is to say, with aproductivity which adapts to the number of objects present on theintermediate conveyor, that is to say, to the filling level of theintermediate conveyor with the objects to be packaged.

In an embodiment, an applying device applies glue on the web ofpackaging material to generate at least one joint and to close acorresponding package. If there are no objects present on theintermediate conveyor, the web of packaging material is fed to thepackaging unit at a linear speed calculated in such a way that the glueremains on the packaging material, before applying pressure to said atleast one joint, for a length of time less than a working life of theglue.

This prevents the glue which has been applied on the packaging materialby the applying device from drying if the infeed conveyor is not able tofeed objects in a sufficiently fast manner, with a consequent need toreject the packages which have not been closed in a reliable manner.

In a second aspect of the invention, there is provided an apparatuscomprising:

-   -   an infeed conveyor for receiving a plurality of objects, having        different dimensions to each other;    -   an intermediate conveyor, arranged downstream of the infeed        conveyor for receiving a flow of objects coming from the infeed        conveyor in an advancement direction;    -   a packaging unit located downstream of the intermediate conveyor        for producing a plurality of packages, each of which containing        an object, starting from a web of packaging material;

wherein along the intermediate conveyor at least one sensor is arrangedfor controlling whether, in the flow of objects advancing along theintermediate conveyor, there are empty positions in which an object ismissing and wherein the intermediate conveyor comprises a plurality ofconveyor belts arrange in sequence along the advancement direction sothat, if an empty position is detected, the objects which follow theempty position are accelerated to fill the empty position.

Owing to the second aspect of the invention, it is possible to obtainthe advantages described above in terms of reducing the waste ofpackaging material and of reducing the stoppages of the apparatus.

The invention can be better understood and implemented with reference tothe accompanying drawings which illustrate a non-limiting exampleembodiment thereof, wherein:

FIG. 1 is a schematic perspective view showing an apparatus forpackaging products with variable dimensions;

FIG. 2 is an enlarged perspective view showing a first part of theapparatus of FIG. 1, wherein some components have been removed for thesake of clarity;

FIG. 3 is an enlarged perspective view showing a second part of theapparatus of FIG. 1, wherein some components have been removed for thesake of clarity;

FIG. 4 is an enlarged perspective view showing a cutting unit of theapparatus of FIG. 1;

FIG. 5 is a side view of the cutting unit of FIG. 4.

FIG. 1 shows an apparatus 1 for packaging objects 2, which are generallyof different types from each other and have dimensions which varybetween one object and another. The apparatus 1 is designed to be usedin the e-commerce field in order to package objects which have beenordered using the Internet before dispatching these objects to thecustomers who requested them. By way of a non-limiting example, theobjects which the apparatus 1 allows to be packed may be books, CDs,items of clothing, items for the home or for free time, and many others.

The apparatus 1 makes it possible to produce, for each object 2, apackage which contains the object 2 and is made of a packaging material,which in the example shown is paper. However, it is also possible to useother packaging materials, such as, for example, plastic film orbiofilm.

The apparatus 1 may comprise an infeed conveyor 3, arranged forreceiving the objects 2 from one or more operators who manually positionthe objects 2 on the infeed conveyor 3. The latter is configured foradvancing the objects 2 along an advancement direction F.

The infeed conveyor 3 may comprise a plurality of infeed belts 4,arranged in sequence along the advancement direction F. In the exampleshown, four infeed belts 4 are provided, even though the number ofinfeed belts 4 may be different.

Each infeed belt 4 is provided with a plurality of positioning notchesor marks 5, which are more clearly visible in FIG. 2, which can beprinted on the infeed belts 4. The positioning marks 5 are positioned ata predetermined constant distance along the advancement direction F, insuch a way as to provide the operator with a visual indication of theposition in which each object 2 must be positioned.

Along the infeed conveyor 3 there is a plurality of work stations 6, ineach of which an operator can work for loading successive objects 2 onthe infeed belt 4 positioned in front of him/her. In the example shown,there are four work stations 6, one for each infeed belt 4, but thiscondition is not necessary. It is possible to provide a number of workstations different from four, for example equal to the number of infeedbelts 4.

Each work station 6 may comprise a platform 7 on which the correspondingoperator can position him/herself to place the objects 2 on the infeedbelts 4.

Each work station 6 further comprises a supporting element 8 suitablefor supporting a crate 9 containing the objects 2 to be packaged. Abovethe infeed conveyor 3 a resting plane 10 is provided on which aplurality of crates 9 full of objects 2 are rested. The resting plane 10may be defined by a motor-driven roller conveyor or by a motor-drivenconveyor belt.

The operator manually picks up a crate 9 from the resting plane 10 andpositions it on the supporting element 8, at the start of his/her workshift or when he/she has emptied a previous crate 9 after positioningall the respective objects 2 on the infeed conveyor 3.

Each work station 6 further comprises a portal 11 which, as shown inmore detail in FIG. 2, includes a detector 12, for example a photocell,arranged for generating a signal when a front edge of an object 2 passesin front of the detector 12. The latter is further configured togenerate a further signal when a rear edge of the object 2 just detectedpasses in front of the detector 12. On the basis of the time between thetwo signals generated by the detector 12 for the same object 2 and ofthe linear speed of the infeed conveyor 3, it is possible to measure thelength of each object 2 in the advancement direction F.

The length of each object 2 is a parameter which will be subsequentlyused to determine the length of the paper with which each object 2 mustbe wrapped. The length of the paper is equal to the length of thecorresponding object 2 measured by the detector 12, to which anadditional value must be added, which ensures that each package can beclosed, at the same time minimising the consumption of packagingmaterial, that is to say, paper.

Each work station 6 may further be provided with a data entry device forallowing the corresponding operator to identify him/herself at the startof his/her shift.

Moreover, each work station 6 may comprise a code reader 56, for readingan identification code present on each product 2 which is positioned onthe infeed conveyor 3. The identification code may be, for example, aone-dimensional bar code or a two-dimensional code, such as a QR code,or other code.

In the work station 6 located in a more advanced position along theadvancement direction F, there is provided a further detector 13 formeasuring the width of each object 2, that is to say, its horizontaldimension perpendicular to the advancement direction F, and the heightof each object 2.

The width and height of each object 2 are used mainly to check that thedimensions of the object 2 fall within a dimensional range which can beprocessed by the devices of the apparatus 1 located downstream of theinfeed conveyor 3.

The apparatus 1 further comprises an object rejecting device 14 locateddownstream of the infeed conveyor 3 for rejecting any non-conformingobjects 2. The object rejecting device 14 is intended in particular forrejecting the objects 2 which, after the measurements performed by thedetectors 12 and by the further detector 13, are found to havedimensions outside the dimensional range which can be processed by theapparatus 1. The object rejecting device 14 is further intended toreject objects 2 which, on the basis of the reading of theidentification code of each object by the code reader 56, are found tohave been incorrectly loaded on the apparatus 1 and are intended to beprocessed in other places.

As shown in FIG. 2, the object rejecting device 14 comprises a tiltableconveyor 15, for example of the belt type, which may be positioned in aconveying configuration C1 or alternatively in a rejecting configurationC2. In the conveying configuration C1 the tiltable conveyor 15 issubstantially horizontal and allows the objects 2 to be conveyed alongthe advancement direction F. In the rejection configuration C2 thetiltable conveyor 15 is, on the other hand, tilted downwards, in such away that an object 2 to be rejected, coming from the infeed conveyor 3,is diverted onto an underlying removal conveyor 16, arranged for movingthe rejected object away from the apparatus 1. At the outfeed from theremoval conveyor 16 a container 17, shown in FIG. 1, may be positionedfor collecting the rejected objects 2. An operator will remove thecontainer 17 when the latter is full of rejected objects, replacing itwith an empty container or repositioning it at the outfeed of theremoval conveyor 16 after the container 17 has been emptied. Thisoperation does not require the apparatus 1 to be stopped andconsequently does not result in loss of productivity.

The object rejecting device 14 may further comprise a passage conveyor18, of the belt type, interposed between the infeed conveyor 3 and thetiltable conveyor 15, for conveying the objects 1 coming from the infeedconveyor 3 on the tiltable conveyor 15.

The apparatus 1 further comprises an intermediate conveyor 19, locateddownstream of the infeed conveyor 3 along the advancement direction F.More precisely, the intermediate conveyor 19 is located downstream ofthe object rejecting device 14.

Downstream of the intermediate conveyor 19 a packaging unit 20 isprovided for producing packages made of packaging material, particularlypaper, each of which encloses an object 2.

The intermediate conveyor 19 is intended for transporting the objects 2coming from the infeed conveyor 3 towards the packaging unit 20 alongthe advancement direction F.

The intermediate conveyor 19 comprises a plurality of conveyor belts 21arranged in sequence along the advancement direction F. In the exampleshown, six conveyor belts 21 are provided, but the number of conveyorbelts 21 included in the intermediate conveyor 19 may be different fromsix. The conveyor belts 21 can be driven at linear speeds (that is tosay, respective movement speeds at which the objects 2 are moved in theadvancement direction F) which may vary over time and which can varybetween one conveyor belt 21 and the other, so as to accelerate or slowdown the objects 2 which the conveyor belts 21 advance, for the reasonsdescribed in more detail below.

The intermediate conveyor 19 further comprises a sensor arrangement 23for detecting the presence of an object 2 on each of the conveyor belts21. The sensor arrangement 23 may comprise a plurality of sensors 24,for example photocells, each of which is suitable for detecting passageof an object 2 close to the sensor 24 considered. The sensors 24 may bepositioned in the transit zones between two consecutive conveyor belts21. A sensor 24 may further be located downstream of the conveyor belt21 in the most advanced position along the advancement direction F.Moreover, a sensor 24 may be positioned upstream of the first conveyorbelt 21, that is to say, upstream of the conveyor belt 21 located at themost rearward position along the advancement direction F.

The intermediate conveyor 19 receives a flow of objects 2 coming fromthe infeed conveyor 3, after these objects have passed through theobject rejecting device 14. In the flow of objects 2 which arrive on theintermediate conveyor 19, there may be empty positions, that is to say,positions in which, contrary to what is expected, an object 2 ismissing.

The empty positions in the flow of objects 2 which arrives on theintermediate conveyor 19 may be due to the fact that, for variousreasons, the operators have been unable to load an object 2 in theposition considered, or they may be due to the fact that anon-conforming object 2 has been rejected in the object rejecting device14, leaving the corresponding position empty.

The sensors 24, which detect the presence of the objects 2 on theintermediate conveyor 19, detect when there is an empty position in theflow of objects 2 which arrive on the intermediate conveyor 19. In thiscase, a control unit of the apparatus 1 accelerates one or more of theconveyor belts 21, arranged downstream of the empty position relative tothe advancement direction F, so as to reduce the distance between theobject 2 which precedes the empty position and the object 2 whichfollows the empty position relative to the advancement direction F. Theobjects 2 are thus compacted along the intermediate conveyor 19 and theempty position is filled by the subsequent objects 2. In this way, theflow of objects 2 which leaves the intermediate conveyor 19 to enter thepackaging unit 20 is a continuous flow, that is to say, a flow whichdoes not have empty positions in which an object 2 is missing.

The control unit can adjust the speed of the conveyor belts 21 in such away that the distance (also known as “gap”) between two consecutiveobjects 2 is controlled, as set by the control unit. Generally speaking,the distance between two consecutive objects 2 is not necessarilyconstant. The distance between two consecutive objects 2 may be selectedas a function of an optimisation logic of the packaging process and mayvary between a minimum value and a maximum value. More in detail, thedistance between two consecutive objects 2 may be selected as a functionof numerous parameters, such as: height of the object 2, length of theobject 2, linear speed of the packaging unit 20, number of conveyorbelts 21 of the intermediate conveyor 19 on which there are objects 2,basic weight of the paper used at that moment in the packaging unit 20,properties of the glue used at that moment in the packaging unit 20,status of certain digital signals present in the work stations 6, statusof certain digital signals received from a line supervision unit or“controller”, and other parameters.

As described in more detail below after having described the packagingunit 20, the intermediate conveyor 19 acts as a buffer, that is to say,as a temporary storage system in which one or more objects 2 aretemporarily stored before transferring them to the packaging unit 20.

As shown in FIG. 3, the packaging unit 20 comprises a packaging conveyor25 for transporting along the advancement direction F the objects 2,wrapped in the packaging material, which in the example shown is paper,while a package is formed around each object 2. The packaging conveyor25 may comprise a plurality of conveyor belts, arranged in sequencealong the advancement direction F. In particular, the packaging conveyor25 may comprise a first conveyor belt 33, located immediately downstreamof the intermediate conveyor 19, a second conveyor belt 34 forsupporting the objects 2 during the packaging process, and a thirdconveyor belt 35 owing to which a plurality of packages 36 containingrespective products can come out from the packaging unit 20. The secondconveyor belt 34 is interposed between the first conveyor belt 33 andthe third conveyor belt 35.

The packaging unit 20 further comprises a supporting core (notillustrated) for supporting a reel 26 of packaging material, morespecifically paper. The reel 26 is housed in a cabinet 27, shown in FIG.1, located on one side of the packaging conveyor 25 and spaced from thelatter.

An unwinding device, not illustrated, is arranged for unwinding from thereel 26 a continuous web 28 of paper, which initially advances in anunwinding direction S which is transversal, more particularlyperpendicular, to the advancement direction F, passing below a platform29 interposed between the cabinet 27 and the packaging conveyor 25.

Along the path from the reel 26 to the packaging conveyor 25, thecontinuous web 28 of paper interacts with a plurality of divertingrollers, having the purpose of modifying a direction of movement of thecontinuous web 28 of paper, which initially coincided with the unwindingdirection S perpendicular to the advancement direction F. Afterinteracting with the diverting rollers, the continuous web 28 of paperis arranged parallel to the advancement direction F, immediately abovethe packaging conveyor 25 (more specifically, above the second conveyorbelt 34), in such a way that the objects 2 coming from the intermediateconveyor 19 and now moved by the first conveyor belt 33 are positionedabove the continuous web 28 of paper.

The packaging unit 20 comprises an applying device 30 for applying onthe continuous web 28 of paper an adhesive substance, particularlypressure sensitive glue, suitable for keeping closed the packages whichwill be formed with the continuous web 28 of paper. The applying device30 may comprise one or more nozzles or spreading elements. The applyingdevice 30 is configured to apply, on the continuous web 28 of paper, alongitudinal strip 31 of glue, which extends, for example continuously,along a longitudinal edge of the continuous web 28 of paper. When thecontinuous web 28 of paper is positioned on the packaging conveyor 25,the longitudinal strip 31 of glue is parallel to the advancementdirection F. The applying device 30 is further configured to apply, onthe continuous web 28 of paper, two transversal strips 32 of glue,positioned transversally, in particular perpendicularly, to theadvancement direction F. The transversal strips 32 may extendcontinuously from a longitudinal edge of the continuous web 28 of paperto the opposite longitudinal edge.

The applying device 30 may be configured to apply on the packagingmaterial a single type of glue, or two types of glue different to eachother. If the applying device 30 applies on the packaging material twodifferent types of glue, the latter may be applied at differentpositions on the packaging material and may have properties and workinglife (or setting times or open times) which are different to each other.

Along the packaging conveyor 25, in particular along the second conveyorbelt 34, two deflector elements 37 are provided having the function offolding two opposite longitudinal flaps of the continuous web 28 ofpaper around the objects 2, in such a way that the continuous web 28 ofpaper forms a tubular enclosure 38 around the objects 2. Thelongitudinal edge of the continuous web 28 of paper having thelongitudinal strip 31 of glue is thus brought above a furtherlongitudinal edge of the continuous web 28 of paper, in order to form alongitudinal joint 39, which extends continuously parallel to theadvancement direction F. Along the longitudinal joint 39, thelongitudinal edges of the continuous web 28 of paper overlap oneanother.

A presser roller 40 is positioned along the packaging conveyor 25, inparticular above the second conveyor belt 34, for applying pressure atthe longitudinal joint 39, in such a way that the glue stably glues thetwo overlapping longitudinal edges of the continuous web 28 of paper.

The packaging unit 20 may further comprise a printing device 41 forprinting, on a portion of the continuous web 28 of paper intended toremain visible, an identification code to which information isassociated relating to the specific object 2 which that portion of paperis intended to wrap. The identification code printed by the printingdevice 41 may be a bar code. In the example shown, the printing device41 is positioned upstream of the presser roller 40.

The printing device 41 may be used to personalise each package 36, thatis to say, to print on each package 36 information specific of thatpackage 36, different from the information printed on the other packages36. For example, the printing device 41 may be configured to print oneach package 36 an identification code, such as a bar code, whichuniquely identifies each package 36 produced (that is to say, each ordermade by a consumer, if the device 1 is used in the e-commerce field). Itis further possible to use the printing device 41 to print on thepackaging material the name of the recipient to whom the correspondingpackage 36 must be sent, and/or its delivery address, and/or any otherinformation useful for tracking the package 36 or for dispatching it.

The packaging unit 20 further comprises a cutting and closing device 42for separating consecutive packages 36 from each other and for closingthe packages 36 transversally to the advancement direction F.

As shown in FIG. 5, the cutting and closing device 42 may comprise acutting blade 43, which extends transversely, in particularperpendicularly, to the advancement direction F to cut the continuousweb 28 of paper, which has been folded to form the tubular enclosure 38,so as to separate two adjacent packages 36.

The cutting blade 43 is interposed between two presser elements 44,which in the example illustrated have a linear geometry and extendtransversely, in particular perpendicularly, to the advancementdirection F. The presser elements 44 are arranged for applying pressureto two portions of the tubular enclosure 38 arranged, respectively,upstream and downstream of the cutting blade 43, on which thetransversal strips 32 of the glue have been previously applied.

In this way, two transversal joints 45 are obtained for closing,respectively, a rear end of one package 36 and a front end of the nextpackage 36.

The cutting blade 43 is positioned above the packaging conveyor 25.Beneath the packaging conveyor 25 an abutment element 46 is arranged,against which the cutting blade 43 abuts for cutting the tubularenclosure 38, and against which the presser elements 44 abut forapplying pressure to the portions of paper intended to be joined by theglue.

The cutting blade 43 and the presser elements 44 are supported by atransversal bar 47 which extends perpendicularly to the advancementdirection F above the packaging conveyor 25.

The transversal bar 47 is movable in a vertical direction, as indicatedby the arrows G, along a pair of guides 48 located at the sides of thepackaging conveyor 25. Also the abutment element 46 is movablevertically, as indicated by the arrows H.

In this way, the transversal bar 47 and the abutment element 46 can movetowards each other, in order to separate two adjacent packages 36 andclose them near the cut, or to move away from each other for disengagingfrom the paper.

The guides 48 are movable forwards and backwards parallel to theadvancement direction F, as shown by the arrows L, owing to a pair ofcarriages 49. In this way, the cutting blade 43 and especially thepresser elements 44 can remain engaged with the tubular enclosure 38 ofpaper for a stretch of the path of the tubular enclosure 38 along theadvancement direction F, so that the presser elements 44 apply pressureto the glue for a sufficient period of time.

After the cutting and closing device 42 has interacted with the tubularenclosure 38, individual packages 36 are separated from the tubularenclosure 38, the individual packages 36 containing respective products.The third conveyor belt 35 removes the individual packages 36 from thepackaging unit 20. As shown in FIG. 3, the dimensions of the packages36, in particular a length measured parallel to the advancementdirection F, are variable between one package 36 and the next one,depending on the dimensions of the object 2 to be packaged.

Downstream of the packaging unit 20 a packages rejecting device 57 isarranged, suitable for allowing non-compliant packages 36 to be removedfrom the apparatus 1.

The packages rejecting device 57 may comprise an initial conveyor 50, atiltable conveyor 51 and a final conveyor 52, arranged in sequence alongthe advancement direction F. The initial conveyor 50 is locateddownstream of the packaging unit 20 for receiving packages 36 from thepackaging belt 25.

The tiltable conveyor 51 is intended to receive the packages 36 from theinitial conveyor 50 and, as shown in FIG. 3, may be arranged in a firstposition P1 or alternatively in a second position P2. In the firstposition P1, the tiltable conveyor 51 is arranged substantiallyhorizontally for conveying the packages 36 coming from the initialconveyor 50 towards the final conveyor 52. In the second position P2,the tiltable conveyor 51 is, on the other hand, tilted downwards, so asto divert the packages 36 downwards, thereby directing them to a removalconveyor 53 located under the final conveyor 52. The packages 36 to berejected fall from the removal conveyor 53 on an underlying box 54,shown in FIG. 1, in which they accumulate. The box 54 shall have to beemptied by an operator when it is full of packages 36 to be rejected.The box 54 may be emptied without having to stop the apparatus 1, so asnot to have loss of productivity.

Along the packages rejecting device 57, a plurality of photocells 55 maybe provided.

During operation, the apparatus 1 starts to operate in an emptyconfiguration, in which no object 2 has yet been loaded on the infeedconveyor 3.

Initially, the infeed conveyor 3 and the conveyors of the objectrejecting device 14 are moved with a linear advancement speed, in theadvancement direction F, which corresponds to the maximum hourlyproductivity Pmax of the apparatus 1. The parts of the apparatus 1located downstream of the object rejecting device 14, relative to theadvancement direction F, are still stationary.

One or more operators, positioned in the respective work stations 6,after being identified by the data input device present in each workstation 6, pick up successive objects 2 from the respective crate 9positioned on the supporting element 8 and place them manually on theinfeed belt 4 located in front of them. Each operator can position eachobject 2 in a free position, of his/her choice, on the infeed belt 4assigned to him/her. The infeed belt 4 carries the objects 2, insuccession, to the portal 11 associated with that infeed belt 4. In theportal 11, the detector 12 measures the length of each object 2, whichhas been loaded on the corresponding infeed belt 4, in the advancementdirection F. Moreover, in each work station 6, the code reader 56 readsthe identification code present on each object 2. This allows a controlunit of the apparatus 1 to track the object 2, that is to say, know theposition of the object 2 on the infeed conveyor 3 (and therefore in theapparatus 1), as well as the data of the object coded in the respectiveidentification code.

In the portal 11 of the work station 6 arranged further downstream thanthe other work stations 6, that is to say, immediately upstream of theobject rejecting device 14, the further detector 13 further allowsmeasurement of the height of the objects 2 which pass at the portal 11and their width perpendicularly to the advancement direction F.

At this point, the control unit compares the dimensions of each object 2with the limit dimensions which the apparatus 1 allows to be processed.The data of the object 2 which have been acquired by the code reader 56are also analysed. If the control unit determines that the dimensions ofthe object 2 are within a range which can be processed by the apparatus1 and that the data of the object 2 acquired by the code reader 56conform to what is expected, the object 2 passes through the objectrejecting device 14 and enters the intermediate conveyor 19. If, on theother hand, the dimensions of the object 2 do not fall within the rangewhich can be processed by the apparatus 1 and/or the data of the object2 acquired by the code reader 56 do not conform to what is expected, thecontrol unit decides to reject the object 2. The tiltable conveyor 15 isthus moved to the second configuration C2 to carry the object 2 on theremoval conveyor 16.

When the first object 2, which has been found to be processable by theapparatus 1 and in accordance with what is expected, enters the objectrejecting device 14, the conveyor belts 21 included in the intermediateconveyor 19 are moved. The first object 2 which arrives on theintermediate conveyor 19 is transported quickly in the advancementdirection F towards the packaging unit 20, which is at this point putinto motion.

The apparatus 1 may now start to package the objects 2 for producing thepackages 36.

During operation, the sensors 24 positioned along the intermediateconveyor 19 control the position of the objects 2 which move in theadvancement direction F to determine whether empty positions are presentin the flow of objects 2 coming from the object rejecting device 14. Ifthis occurs, the conveyor belts 21 accelerate the objects 2 which followthe empty position, in such a way that the latter is filled, that is tosay, in such a way as to generate a flow of objects 2, entering thepackaging unit 20, in which there are no empty positions. This ensuresthat, in the packaging unit 20, empty packages are not produced due tothe presence of empty positions in the flow of objects 2 coming from theinfeed conveyor 3.

By acting on the linear speed of each conveyor belt 21, which may bechosen independently of the linear speed of the other conveyor belts 21,it is ensured that the distance between two consecutive objects 2entering the packaging unit 20 is controlled, on the basis of theparameters listed previously.

The conveyor 19 acts as a phasing and distance controlling conveyor,since it positions the objects 2 one after the other in the advancementdirection F, in such a way that there are no empty positions in the flowof objects 2 which enter the packaging unit 20 and in such a way thatconsecutive objects 2 which enter the packaging unit 20 are atcontrolled distances.

Each object 2 which enters the packaging unit 20 is detected by aninfeed detector 58, shown in FIG. 3, which activates the applying device30 so that the latter applies the glue on the continuous web 28 ofpaper, in zones of the paper intended to form the package 36 which willwrap the object 2 at issue.

Since a continuous flow (that is to say, without empty positions) ofobjects 2 enters in the packaging unit 20, a continuous queue of objects2 is generated in the packaging unit 20, the objects 2 of the queuewaiting to be packaged and positioned upstream of the cutting andclosing device 42. This continuous queue corresponds to a strip ofpaper, unwound from the reel 26, to which the glue has already beenapplied in the appropriate positions for closing the packages 36 inwhich the objects 2 will be enclosed.

The glue has a working life or setting time or open time, that is tosay, a time during which the portions of paper to be joined must besuperposed and pressed against each other, so that the glue can set andform a sealed joint.

The open time depends on the type of glue used and is usually severaltens of seconds. In order to have reasonable certainty that the packages36 remain closed, the interval of time between the moment the glue isapplied to the continuous web 28 of paper by the applying device 30 andthe moment in which pressure is applied to superposed portions of paperto be glued, by the presser roller 40 and to the presser elements 44,has to be less than the open time of the glue.

The speed of the packaging unit 20 is linked to the speed of theintermediate conveyor 19. More specifically, the speed of the packagingunit 20 adapts, that is to say, it decreases or increases automatically,according to a logic which will be explained below.

As mentioned above, the intermediate conveyor 19 acts as a buffer, thatis to say, as a temporary storage zone in which a controlled number ofobjects 2 are temporarily stored, waiting to enter the packaging unit20.

If a flow of objects 2 arrives on the intermediate conveyor 19 with aspeed, intended as number of objects 2 per hour, which is equal to themaximum hourly productivity Pmax of the apparatus 1, a predeterminedfilling level is maintained on the intermediate conveyor 19.

“Predetermined filling level” means a predetermined value of the ratiobetween the space on the intermediate conveyor 19, measured along theadvancement direction F, occupied by objects 2 positioned at controlledrespective mutual distances, and the total space available for theobjects 2 on the intermediate conveyor 19, in the advancement directionF.

In other words, the filling level is the ratio between the longitudinaldimension of the intermediate conveyor 19 on which, at the consideredmoment, objects 2 are present which are placed at controlled respectivemutual distances, and the total longitudinal dimension of theintermediate conveyor 19.

In the illustrated embodiment, the predetermined filling level which ismaintained on the intermediate conveyor 19 may be an average fillinglevel, for example equal to approximately three conveyor belts 21 ofsix. This means that a predetermined number of conveyor belts 21adjacent to the packaging unit 20 is kept occupied by objects 2, whilethe remaining conveyor belts 21 closest to the object rejecting device14 are empty.

The packaging unit 20, which is consequently fed with a number ofobjects per hour which is a substantially constant (and equal to themaximum hourly productivity Pmax of the apparatus 1) in the interval oftime considered, adapts its linear speed, that is to say, the linearspeed of the first conveyor belt 33, of the second conveyor belt 34 andof the third conveyor belt 35, taking into account only the differentlength of consecutive objects 2 in the advancement direction F. In otherwords, the linear speed of the packaging unit 20 is adjusted instant byinstant, taking into account the length of the objects 2 to be packaged,to ensure that the set hourly productivity is complied with, which inthe case considered is equal to the maximum hourly productivity Pmax.The linear speed of the packaging unit 20 is adjusted in such a way thatthe number of packages 36 coming out from the packaging unit 20corresponds to the maximum hourly productivity Pmax.

If, as realistically occurs, the flow of objects 2 which enter theintermediate conveyor 19 varies continuously, for example because thereare empty positions in this flow, the linear speed of the conveyor belts21 is adjusted in such a way that the empty positions are filled, byaccelerating the objects 2 which follow the empty positions relative tothose preceding them. By modifying the linear speed of the conveyorbelts 21, it is possible to keep under control, equal to desired values,the distance between consecutive objects 2 which enter the packagingunit 20. The latter will work with a variable speed, meaning both linearspeed and hourly productivity, depending on the number and dimensions ofthe objects 2 which the packaging unit 20 receives from the intermediateconveyor 19 in the unit of time.

The speed of the packaging unit 20 is in this case selected to keep inthe intermediate conveyor 19 a predetermined filling level, that is tosay, a predetermined value of the ratio between the longitudinaldimension of the intermediate conveyor 19, measured in the advancementdirection F, occupied by objects 2 that are positioned on theintermediate conveyor 19 at a controlled mutual distance, and the totallongitudinal dimension of the intermediate conveyor 19, measured alongthe advancement direction F and available to receive the objects 2.

In the illustrated example, the predetermined filling level correspondsto a predetermined number of conveyor belts 21 occupied by the objects2. This filling level may be, for example, 50%, that is to say,corresponding to three conveyor belts 21 out of six which are occupiedby objects 2.

If the number of objects 2 which are received from the intermediateconveyor 19 in the unit of time decreases in a very marked manner andfalls below a predetermined value, for example because the number ofoperators present in the work stations 6 has reduced, the control unitis configured to ensure that the number of conveyor belts 21 on whichobjects 2 are present is minimal. For example, it is possible to ensurethat the objects 2 accumulate only on a conveyor belt 21 immediatelyupstream of the packaging unit 20, or that they are even transferredimmediately to the packaging unit 20 without accumulating objects 2 onthe conveyor belts 21. This result is obtained by adapting the speed ofthe packaging unit 20.

More specifically, the packaging unit 20 slows down its speed, meaningin this case the productivity, that is to say, the number of packagesformed per unit of time. In particular, the productivity of thepackaging unit 20 is in this case determined on the basis of the workinglife or open time of the glue applied by the applying device 30. Inother words, under conditions of low flow of objects 2 entering theintermediate conveyor 19, the parameter which determines the speed ofthe packaging unit 20 is no longer the filling level of the intermediateconveyor 19, but becomes the working life or open time of the glue. Thatis to say, in these conditions, the packaging unit 20 works at thelowest production speed compatible with the open time of the glue. Inother words, the speed of the packaging unit 20 is adjusted in such away that the time the glue remains on the paper, before the respectivejoints are closed, is less than the open time of the glue.

If no other objects arrive on the intermediate conveyor 19, thepackaging unit 20, proceeding at a low speed as described above,compatibly with the open time of the glue, packages all the objects 2present in the packaging unit 20 upstream of the cutting and closingdevice 42. The packaging unit 20 is thus progressively emptied.

When objects 2 to be packaged are no longer present in the packagingunit 20, the packaging unit 20 stops while waiting to receive newobjects 2 from the intermediate conveyor 19.

When the flow of objects 2 on the intermediate conveyor 19 isre-activated, the packaging unit 20 returns to operation, guaranteeinghowever that the paper present in the packaging unit 20, which hasalready been unwound from the reel 26 and corresponds to emptypositions, in which no objects 2 were present, is rejected at theoutfeed of the packaging unit 20, as if it were an empty package, usingthe packages rejecting device 57.

The start of the packaging unit, from an empty configuration of theapparatus 1, can further be controlled by adopting other types of logicwhich are more sophisticated than the one described above. For example,the packaging unit 20 may be controlled in such a way as to restart onlywhen a predetermined number of objects 2 has accumulated on theintermediate conveyor 19. This predetermined minimum number of objects 2may in turn be defined on the basis of a criterion or an algorithm whichtakes into account various parameters, such as number of operatorspresent in the work stations 6, number of objects 2 which are enteringthe infeed conveyor 3, sum in millimetres of the lengths of all theobjects present in a predetermined initial portion of the apparatus 1,and others. The aim is to restart the packaging unit 20 only when thereis reasonable certainty that there is a significant number of objects 2at the infeed, so as to prevent the packaging unit 20 from stoppingagain, within a short space of time, which would result in unnecessarywaste of paper.

In the embodiment of the apparatus 1 which has been described above,reference has always been made to an intermediate conveyor 19 comprisinga plurality of conveyor belts 21 arranged in sequence along theadvancement direction F, wherein any empty position along theintermediate conveyor 19 is filled by increasing the speed of at leastone conveyor belt 21 which conveys the objects 2 following the emptyposition, relative to the speed of at least one further belt conveyor 21which conveys the objects 2 preceding the empty position.

However, it is possible to fill any empty position along theintermediate conveyor 19 and/or position the objects 2 at controlledmutual distances along the intermediate conveyor 19, also by adoptingprocedures different from the increase in the speed of a subsequentconveyor belt 21 relative to a preceding conveyor belt 19.

1. A method comprising the steps of: positioning a plurality of objects,having different dimensions to each other, on an infeed conveyor;delivering to an intermediate conveyor a flow of objects coming from theinfeed conveyor and movable along an advancement direction; feeding apackaging unit with the objects coming from the intermediate conveyor,the packaging unit producing a plurality of packages, starting from aweb of packaging material, each package containing one of said objects;the method further comprising the step of checking if, in the flow ofobjects which advance along the intermediate conveyor, there are emptypositions in which an object is missing and wherein, if an emptyposition is detected, there is provided filling the empty position byaccelerating the objects which follow the empty position relative to theobjects which precede the empty position, wherein the intermediateconveyor comprises a plurality of conveyor belts arranged in sequencealong the advancement direction and wherein, if the number of objectsarriving on the intermediate conveyor in the unit of time is greaterthan or equal to a predetermined value, the production speed of thepackaging unit is adjusted in such a way as to keep in the intermediateconveyor a predetermined average filling level.
 2. The method accordingto claim 1, and further comprising the step of controlling the speed ofthe conveyor belts in such a way as to arrange the objects at acontrolled distance from each other at the infeed of the packaging unit.3. The method according to claim 1, wherein the objects which follow theempty position are accelerated by increasing the speed of at least oneconveyor belt which transports the objects which follow the emptyposition relative to the speed of at least one further conveyor beltwhich transports the objects which precede the empty position.
 4. Themethod according to claim 1, wherein the intermediate conveyor acts as abuffer in which a plurality of objects is temporarily accumulated whilewaiting to enter the packaging unit.
 5. The method according to claim 1,wherein the predetermined average filling level corresponds to apredetermined value of the ratio between a longitudinal dimension of theintermediate conveyor, measured in the advancement direction, occupiedby objects which are positioned on the intermediate conveyor at acontrolled mutual distance, and a total longitudinal dimension of theintermediate conveyor along the advancement direction available forreceiving the objects.
 6. The method according to claim 1, wherein thepredetermined average filling level corresponds to a predeterminedaverage number of conveyor belts filled with the objects.
 7. The methodaccording to claim 6, wherein the average filling level corresponds tohalf of the conveyor belts filled with the objects.
 8. The methodaccording to claim 1, wherein the web of packaging material is fed tothe packaging unit with a variable linear speed which is determined onthe basis of the number of objects which the packaging unit receivesfrom the intermediate conveyor and on the basis of the length of eachobject in the advancement direction.
 9. The method according to claim 1,wherein an applying device applies glue on the web of packaging materialto generate at least one joint and to close a corresponding package andwherein, if the number of objects arriving on the intermediate conveyorin the unit of time is less than or equal to a predetermined value, theweb of packaging material is fed to the packaging unit with a linearspeed calculated in such a way that the glue remains on the packagingmaterial, before applying pressure to said at least one joint, for alength of time less than an open time of the glue.
 10. The methodaccording to claim 1, wherein the objects have been purchased throughthe Internet and are packaged in the packaging unit before beingdispatched to the people who ordered them.
 11. The method according toclaim 1, wherein the packaging material is paper.
 12. An apparatuscomprising: an infeed conveyor for receiving a plurality of objects,having different dimensions to each other; an intermediate conveyor,located downstream of the infeed conveyor for receiving a flow ofobjects from the infeed conveyor in an advancement direction; apackaging unit located downstream of the intermediate conveyor forproducing a plurality of packages starting from a web of packagingmaterial, each package containing one object; wherein along theintermediate conveyor at least one sensor is arranged for controllingwhether, in the flow of objects advancing along the intermediateconveyor, there are empty positions in which an object is missing and inthat the intermediate conveyor comprises a plurality of conveyor beltsarranged in sequence along the advancement direction so that, if anempty position is detected, the objects which follow the empty positionare accelerated to fill the empty position, the production speed of thepackaging unit being adjustable in such a way as to keep in theintermediate conveyor a predetermined average filling level.
 13. Theapparatus according to claim 12, and further comprising an objectrejecting device interposed between the infeed conveyor and theintermediate conveyor, the object rejecting device comprising a tiltableconveyor which can be positioned in a first configuration, in which thetiltable conveyor is arranged horizontally for conveying the objectsfrom the infeed conveyor to the intermediate conveyor, the tiltableconveyor being further positionable in a second configuration in whichthe tiltable conveyor is tilted downwards to divert the objects on aremoval conveyor.
 14. The apparatus according to claim 12, wherein thepackaging unit comprises an applying device for applying glue on the webof packaging material, a plurality of deflector elements for folding theweb of packaging material and forming a tubular enclosure around theobjects, at least one presser for applying pressure to overlyingportions of the web of packaging material on which the glue is present,a cutting blade for separating successive packages from the web ofpackaging material.